The present invention generally relates to tube suspension systems and, more particularly, is concerned with a tube suspension assembly for use in superconductive magnets.
Superconductive magnets include superconductive coils which generate uniform and high strength magnetic fields, such as used, without limitation, in magnetic resonance imaging (MRI) systems employed in the field of medical diagnostics. The superconductive coil assemblies of the magnet are enclosed in a thermal shield surrounded by a vacuum enclosure.
Various designs of tube suspension systems are employed to support the superconductive coil assembly of the magnet from and in spaced apart relation to both the thermal shield and the vacuum enclosure of the magnet. As one example, the tube suspension system can include overlapped fiberglass outer and inner support cylinders, such as disclosed in U.S. Pat. No. 5,530,413 to Minas et al. which is assigned to the same assignee as the present invention. In the Minas et al. suspension system, the outer support cylinder is located within and generally spaced apart from the vacuum enclosure and positioned outside of and generally spaced apart from the thermal shield. A first end of the outer support cylinder is rigidly connected to the vacuum enclosure while a second end of the outer support cylinder is rigidly connected to the thermal shield. The inner support cylinder is located within and generally spaced apart from the thermal shield and is positioned outside of and generally spaced apart from the superconductive coil assembly. The inner support cylinder has a first end rigidly connected to the thermal shield near the second end of the outer support cylinder and has a second end located longitudinally between the first and second ends of the outer support cylinder and rigidly connected to the superconductive coil assembly.
Problems can occur, however, with some designs of tube suspension systems at cryogenic temperatures. For instance, high stresses can result at joints between dissimilar materials of the tube suspension system and the metallic magnet components which severely limit the load carrying capacity of the tube suspension system. Also, large differential thermal contraction between the tube suspension system and the metallic magnet components can cause failure of the tube suspension system.
Consequently, a need exists for innovation with respect to tube suspension systems for superconductive magnets which will provide a solution to the aforementioned problems.